Three reasons your mower won't start and what to do about it

Consumer Reports News: April 04, 2013 02:38 PM

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For northerners that lovely time of year between shoveling snow and mowing the lawn is about to end. And now, before the blades of grass reach an unsightly height, is the best time to make sure your mower is in working order. If you put it away in a rush last fall and didn't do it properly, you may be in for a rude awakening or a trip to the repair shop. Here's how to make sure you can fire up your mower and keep it running smoothly through the season.

Gas is too old. If you ran your walk-behind mower dry or siphoned out the unused gas in the fall, just fuel up with fresh gas—and we don't mean gas that sat in the can all winter. Be sure to mix fuel stabilizer in with the gas before filling the mower. If you did leave gas in the tank, siphon out as much as possible before fueling up with fresh, stabilized gas. The engine should start, although maybe not on the first try.

Because the fuel tank of a riding mower doesn't drain out the bottom, having left a little gas in the tank isn't as much of a problem. Of course, if the tank is full, siphon out what you can before filling up with fresh, stabilized gas.

Battery is dead. Charging the battery of an electric mower is essential before starting it. And most manuals advise keeping the battery warm on a trickle charge over the winter. Batteries on lawn tractors or other riding machines also need charging. And if you have a walk-behind gas mower with electric start, chances are you'll have to charge the starting system's battery before that feature works; the alternative is pull-starting.

Spark plug is funky. Spark plugs typically get replaced every 100 hours of operation, but if you haven't been keeping track, replace them annually. The only tricky part is learning how to "gap" it correctly. Use a spark plug gauge to measure the gap between the two electrodes at the tip of the spark plug. Many small engines require a .030-inch gap but check your owner's manual to be sure. If you're uncertain, buy the plug at a dealer who'll gap it for you. Without the proper gap the engine might run badly if it starts at all.

Mower maintenance
Maintaining your mower can make all the difference between starting the machine and cursing its impertinence. Once it's humming you can keep it that way by following this advice from our experts.

  • Keep blades sharp. You should sharpen your mower's blades monthly. This keeps the engine from working harder, which affects its lifespan. Keeping a spare on hand helps. Sharp blades also keep your grass looking sharp.
  • Change the oil. Do it at least once a season when the gas tank is empty, although riding machines have a special drain plug so you don't have to tip the machine.
  • Change filters. If you have a walk-behind mower, replace the air filter. For larger gear it's more complicated: If the air filter is paper, replace it. If foam, wash it in soap and water, rinse and squeeze it dry. Check your owner's manual. Some suggest you also oil a foam filter using engine oil. If so, squeeze the filter dry again before reinstalling it.

Best new mowers
Alas, there are some mowers that can't be saved. If yours is one of them, check the results of Consumer Reports mower tests. Our top picks include 23 riding mowers and 25 walk-behind models. Our rider Ratings and recommendations include conventional, wide-deck, zero-turn-radius and rear-engine rider models including 10 CR Best Buys that range in price from $1,300 to $2,800. The walk-behind mowers that earned CR Best Buys range in price from $220 to $400.

An electric mower might do the trick for homeowners with small properties and you can dispense with the messy fueling routine. The self-propelled Black & Decker SPCM1936 made list of recommended mowers. It was very good at mulching, handling and side-discharging. The electric push mowers we liked best include the Black & Decker CM1936, Black & Decker CMM1200 and the Toro 20360. We also liked the corded Black & Decker MM875.

Ed Perratore

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